*Putting* water in your DC collection bin?

Okay, this is probably is going to strike most of you as a horrific
idea... but the more I thought about it, the more sense (or, at least,
the less nonsense) it made.
Back when I was making my own Biesemeyer clone
(http://joe.emenaker.com/Table-Saw%20Fence/Table-Saw%20Fence.html ), I
was cutting a lot of angle-iron and steel tubing on my RAS fitted with
a metal-cutting wheel. Boy, did that thing make sparks like the
dickens! I thought it was going to ignite the sawdust which had
accumulated behind the RAS from earlier projects.
Well, I'm about to buy a DC and make my own cyclone for it. It struck
me that I'd be *asking* for trouble if I tried cutting metal with a DC
hooked up and running.
But what if I had a cyclone which emptied into a bin with a little
water in it? The water would catch all/most of those sparks. Not only
that, but it would be nice just for plain wood chips, since it would
help keep them under control when you detatch the bid to dump it
out... and it would help guard against some other DC-related fire
hazards (like hitting a nail or something).
So, I figured I'd ask: Does anybody out there *do* this?
Alternatively, has this been discussed before?
- Joe

I used to have an old Allis Chalmers tractor that had a glass jar
as part of the air filtering mechanism, maybe was supposed to be
filled with (what?) to catch things going by, but I think the water
would rapidly turn into slightly moist sawdust and a hard cake.

Hi Dave,
You are right about ending up with sawdust cake. I tried it in a plastic
receiver as an attempt to knock down the small dust particles as they
impinged on the surface. It works but the rapid passage of high volumes
of air caused the water to evaporate very quickly. Very moist air going
through the blower et al is not going to do it much good either. Cheers,
JG
Dave Hinz wrote:

On your tractor, that glass jar was supposed to be filled with ....
air. The use of glass jars as dust traps was a simple, easily replaceable
mechanism for filtering air prior to the engine intake. It may also have
had an adjunct oil-bath air cleaner that used oil to further trap
particles.

It did, indeed, have an oil-bath air cleaner. Nice little old tractor, but
that magneto was a perpetual problem. It has gone to a better place now,
though. (No, really, a friend who collects 'em bought it for parts to
restore another of the same type).
Dave

What, spontaneous combustion in moist wood-like substances, or from
someone specifically in this situation you mean?
It's certainly not much different from any other wet hay-like situation.
And I have stuck my hands into a pile of fresh sawdust to find it was
warm inside.
Dave Hinz

I would, my top-posting friend, but you've quoted in such a way to
make it inconvenient. Also, whatever your point may be is masked by
your apparent attitude, so I can't see much point. Maybe you're saying
that moist sawdust is different somehow from moist sawdust?

Are you bottom-posting because your brains are there?
As I said before, it is volatile organics produced by _GREEN_ hay or manure,
or sawdust which ignite.
It is a chemical reaction, and those chemicals are no longer present in hay
properly crimped and dried, or as the question to which you allegedly
replied, previously dried wood shavings.
You're sitting in front of a reference library, why not look up the real
answer instead of displaying your ignorance and then trying to defend it
with ad hominem bullshit (which ignites less readily than horse, because
cattle are more efficient in their digestion).
http://www.gov.on.ca/OMAFRA/english/livestock/dairy/facts/hayfires.htm
And any number of places.
wrote:

Yes, I'm familiar with wet hay fires. Are you going on record as saying
damp sawdust cannot spontaneously combust? How sure are you of this?
Showing that hay combusts for reason (A), and showing that sawdust does
not have reason (A), does not mean sawdust does not spontaneously combust,
it just means it doesn't spontaneously combust _for that precise
reason_. Yes?

I'm going to have to go with Dave on this, growing up my dad was the fire
chief in a rural town in eastern ID, my grandfather was the fire chief in
Rexburg( 3 miles away), according to them you should NEVER leave wet
Organic material, hey, sawdust, grass clipping, etc. where they can't dry,
they'll begin to rot which makes heat, then they start to smolder, and as
soon as there exposed to air (like dumping the container) they'll burst
into flames, ever wonder why the trash company doesn't want to take yard
clipping?
Dave Hinz wrote:

Does that mean I can't put them in a closed compost bin then? They surely
won't dry there (but they will get pretty warm).

My trash company takes yard waste. One can either rent a bin
from the City or pile the stuff in the street for pickup.
scott
(However, I just emptied the DC into the compost pile last weekend, and
within a couple of hours, the chips (on the top of the pile) were at well
over 110 degree F - Now, mind you, I was jointing and planing both green
2x6's and KD studs, so there was definitely green wood in the pile).

Did you do any search at all, or read the material I referenced?
Did you catch the significance of the CRITICAL temperature? 100 C / 212 F
is the boiling point of water, which, up until that temperature is reached,
has been cooling the mass by evaporation, preventing ignition. You see, wet
hay, even when green, has to dry out before it can combust.
As I look out to the north I see round bales stretching across the next 40.
All have great bulk to provide insulation, all are undeniably wet, and none
are flaming, because the volatile organics which cause spontaneous ignition
are not there.
Oh yes, you put out a hay fire with water.

Yep, on record as saying that, absent the volatile organics which are the
source of the ignition, you have wet sawdust, which won't burn on its own or
with a flame until the water is expelled. Fresh sawdust and fresh hay
outgas the same.
The wonderful thing about science is that there is a cause - effect,
reproducible outcome.
You find yourself approached to serve on many product liability juries?
Seems you're what the ambulance chasers would like.
wrote:

George, comments like that make it clear that you can't stand to have anyone
disagree with you and when you can't convince someone with facts and
figures (and you're not going to with the kind of assertions you're making
because you're assuming that the existence of one mechanism of ignition
precludes the existence of others and further, you're arguing that in the
presence of unknowns one should take the dangerous path rather than then
safe one) you'd rather insult them than agree to disagree and get on with
your life.
If science knew everything then the scientists would be out of a job.
Remember that.

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